Does anyone know how compatible the two are? Spline count and bolt patterns?

I have an Ax5 mated with a 2.5L, it's ready to die. How hard is it to rebuild those?) If I found a Ax15 in a Junkyard, I would love to grab one if it could work with my setup. I'm not ready to gung-ho with a full advanced adapters kit, but something as simple as a shaft change or other mod would be helpful.